# Re: \[PATCH 13/17\] watch\_queue: Implement mount topology and attribute change notifications \[ver \#5\]

- From: Miklos Szeredi \<miklos@szeredi.hu\>
- Date: 2020-08-03 10:02:42 
- List: linux-security-module
- Page: https://ratatoskr.run/linux-security-module/2020/08/185811
- Thread: https://ratatoskr.run/keyrings/2020/03/175521/t.md

```text
On Fri, Jul 24, 2020 at 1:36 PM David Howells [ref] wrote:
>
> Ian Kent [ref] wrote:
>
> > I was wondering about id re-use.
> >
> > Assuming that ids that are returned to the idr db are re-used
> > what would the chance that a recently used id would end up
> > being used?
> >
> > Would that chance increase as ids are consumed and freed over
> > time?
>
> I've added something to deal with that in the fsinfo branch.  I've given each
> mount object and superblock a supplementary 64-bit unique ID that's not likely
> to repeat before we're no longer around to have to worry about it.
>
> fsinfo() then allows you to retrieve them by path or by mount ID.

Shouldn't the notification interface provide the unique ID?

Thanks,
Miklos

>
> So, yes, mnt_id and s_dev are not unique and may be reused very quickly, but
> I'm also providing uniquifiers that you can check.
>
> David
>
```